The objective of the proposed research is to explore the behavior in vivo of poly(hydroxyalkanoates) scaffolds for tissue engineering with nuclear magnetic resonance (NMR) spectroscopy and imaging techniques. Structural and chemical changes induced in bioabsorbable porous matrices of poly(hydroxyalkanoates) implanted in rats will be assessed with NMR. 1H NMR imaging techniques will be utilized to map the content and hydrodynamic behavior of water in the polymeric matrices in order to study the growth of tissue in the implants. Multinuclear (1H and 13C) solid and solution NMR spectroscopy will be used to characterize the degradation of the polymers. Biodegradable polyesters are polymers of growing interest in the field of temporary surgical and pharmacological applications, since they do not require removal after their function is completed. These polymers can be utilized as templates for cell transplantation and regeneration of metabolic organs and structural tissues. Poly(hydroxybutyrate) (PHB) and its copolymers are biodegradable in various environments and have shown excellent biocompatibility. Although the reaction mechanisms involved in the biodegradation of PHB in vitro are known, its degradation in vivo is poorly understood. Moreover, dynamic information about the morphology and its correlation with chemistry during degradation of polyhydroxyalkanoates is nonexistent. This information is crucial to understanding the behavior in vivo of implants based in these polymers. NMR is a noninvasive analytical technique that will allow the characterization of these changes. The results of this investigation should provide the basic knowledge to design novel porous matrices of PHB for tissue and organ regeneration, such as liver. The methodology developed will be applicable to study of other bioabsorbable implants for tissue engineering, orthopaedic and drug delivery applications.